200MW四角切圆锅炉燃烧器浓淡比对NOx排放影响的数值研究

摘要

以某热电厂200 MW四角切圆浓淡煤粉燃烧锅炉为对象,通过数值模拟获得了该炉最大连续出力工况(BMCR)下炉膛内的流场、温度场及炉膛出口的NOx浓度,并进一步通过数值模拟探讨了改变水平浓淡煤粉燃烧器浓淡比时对炉内燃烧及NOx生成情况的影响.数值结果表明:在BMCR工况下,计算值与实际运行的在线仪表的记录值基本一致;当浓淡比增大时,NOx生成量并不是单调的,而是先降低后升高;其中最佳浓淡比为5:1,且在此基础上采用“缩腰型”配风有助于进一步降低NOx生成量.其计算结果可供同类锅炉实际运行时参考.%Taking a 200 MW tangentially coal-fired boiler as an investigated object,numerical simulation methods were used to study the boiler maximum continous rating (BMCR) condition and NOx emissions in different pulverized coal shades,and the furnace flow field,temperature field and the characteristics of NOx emissions were thus acquired.It turns out that under BMCR condition,the numerical calculating results can meet the design values in a better way.The main cause of the higher concentration of NOx emissions is that the chamber excess air coefficient is large and the dual-channel burner's high NOx emission characteristic is obvious.The best shade of pulverized coal in the actual operation is 5:1.The calculation results can be used as an operation reference for similar boiler.